Hyperion's new engine

Hyperion, a C&C 27 Mk I, received an upgrade from her original Atomic 4 to a Yanmar 2GM20 after the original engine failed in "uncomfortable circumstances". Fitting this engine, says owner Ralph Ainslie, demands a minimum of work, and the only task beyond the average owner was the creation of a new S/S exhaust, which Ralph says could be done at reasonable cost by any welding shop. Complete comments below.

The bottom three pictures show a similar installation on Towser, a Mk IV
whose A4 failed. The engine here is a Yanmar 2YM15 – slightly less powerful than the 2GM20, but still more than adequate to moving a 27. The 2YM15 fits well into the A4's space, and is easy to service despite having its oil filter and dipstick on the starboard side. Noise was a surprise; the 2YM15 is supposed to be relatively quiet, but compared to an A4, makes an unbelievable clatter. The addition of foam noise insulation brought sound levels down to a reasonable level.

Top view

Front view

Motor mounts

Exhaust manifold & muffler

Waterlift muffler & riser

Waterlift 2

Gooseneck

Control panel

Engine starboard side

Shift & throttle control

Exhaust watertraps

"This winter, I replaced Hyperion's engine with a new Yanmar 2GM20 2-cylinder, 18HP diesel. The reason for the replacement is that the original Atomic Four had failed on me twice in uncomfortable circumstances.

Questions about replacement engines have come up in the Forum several times and I wanted to show people what is involved. The diesel itself was about $7500.00 Cdn. I did the complete installation myself, therefore I have no idea of the labour cost that would be involved. The swap, however, was a piece of cake for me. If you're not as mechanically inclined as I am, it might not be quite so simple, but note that this engine fits with no major modifications to the engine space and no glass work. The Yanmar 2GM20 even comes with a complete wiring harness that just plugs in, so the amount of work is minimal.

As far as making up the exhaust gooseneck, any competent welding shop can do it and I don't believe it would be all that expensive. Use Sch. 10 316 Stainless Steel material. The wall thickness is not that much.

At the same time as I changed the
engine, I replaced the prop for a
beautiful feathering prop made by
Max-prop ($2200.00 Cdn. landed here).
I had the prop manufacturer match
the prop to the boat and the engine.
Prop is 2 blades of 13" diameter
set at 28 degrees of pitch [equivalent
to 13"pitch]. I also increased the
length of the shaft about an inch
to give me proper clearance between
the prop blade and the hull.

I replaced my tank with one I had made out of stainless steel to original dimensions. When I removed the 30-year-old tank, I could poke my finger through the bottom. Scared the daylights out of me.

There are a lot of people out there that would say I am crazy for spending the money on a 1971 Mk1 (I have spent more on improvements than I paid for the boat), but my wife and I love the performance of the boat and I have no intentions of ever selling it or moving up."

 Ralph AinslieHyperion
March, 2004

Thoughts on costs

Recently (Feb. 2008),
a BC owner was quoted $7500 for a Yanmar and $5000
for the installation (at a $70/hr rate), which he found
discouraging. However, while it might cost several
thousand dollars of a mechanic's time to do the job,
installation doesn't need to be done by a mechanic.
Rather than abandon the thought of a new engine, it
was suggested, he should do the work himself, as Ralph
Ainslie did. There is nothing in an engine change that
anyone who is reasonably competent with tools cannot
do. My perception after watching some of
the work being done on my boat and doing some of it
myself (and saving quite a bit thereby), is that if
you can confidently look after an engine (change oil
and filters, winterize, etc.), you can swap one of
these engines into the boat with the help of a friend.

There is one complication – the competing needs
of getting the old engine out and the new one in, which
is easily done with a club mast jack or even the boat's
own boom and a block-&-tackle (in other words,
on the water), versus the need to have the boat out
of the water to replace the shaft (not obligatory
but desirable, as you'll probably find the old one
is quite worn and a new shaft can be a bit longer,
allowing you to position the engine slightly farther
forward); it's nice to replace the cutless bearing
too. Also, you will have to resize the exhaust fitting
on the transom. These competing needs could be dealt
with through a bit of planning or – something sailors
are good at – improvisation.

You can remove an A4 more easily by removing the wood
cross-piece that supports the front of the engine cover.
You will have much more room to work. Also, you can
lift the engine straight out with a crane. You will
need a #1 or #2
Robertson head screwdriver ( a variation is apparently
sold in the US by Home Depot as a "square drive" screwdriver).
There are three or four screws a side and then the cross-piece
just lifts out. The engine is gearcase-heavy and will
bind on the mounting bolts if you just try to lift it
with the lifting eye on
top of the block. Instead, drop a strop three or
four feet from the lifting hook to the hoisting eye.
Then, from the same hook, drop a block and tackle and
make it fast at the rear of the gearcase; the block and
tackle should make a slight dog-leg as it passes under
the cockpit. With everything disconnected on the engine,
tighten the block and tackle until the aft end of the
engine rises. It's okay if it binds a little bit on the
mounting bolts, but not too much. Raise the hook a bit
until the front end of the engine binds a bit. Repeat
until the engine is off the mounts and hanging free.

The Yanmar 2GM and 2YM engines are virtually a drop-in replacement. You
don't touch the glass (see Ralph's comment above). The steel angles on
top of the fibreglass or wood beds need to be changed, but anyone who
can use a measuring tape and hold a hacksaw and a drill can do that.

If you have a steel tank you must replace
it (see Ralph's comment above – original steel
tanks are way past their best-by dates and so are some
aluminum ones). If you have an aluminum tank, you're
not off the hook; these can develop pinholes thanks
to corrosion from within or, more commonly, from prolonged
contact with wetness from the base on which they are
mounted. You should lever it up and inspect the underside
for corrosion before you start the engine replacement
process, because the easiest time to get a tank out
is through the engine bay. A
replacement plastic tank will cost between $100 and
$200.

Cleaning a tank is sometimes made out to
be a big deal, but all you have to do is take the fuel
sender off the top and you've got a hole large enough
to insert a pump hose into the tank and, when the tank
has been drained, to insert a dowel wrapped in paper
towel – this
will blot up any bits of crud on the tank bottom. You
don't have to get every bit of the gas out. A diesel
will easily tolerate a concentration of gas as high
as a litre in the 50-litre tanks on a 27.